NSURLRequest with multiple parameters

Question

I am trying to set up a NSURLRequest to download a simple index.html with its externa style.css sheet but I am not quite sure how to do this.. I have only ever just formatted the URL of the request to the file I want.. but this has to be slightly different and I cannot find a good example of what I am trying to do.

this is my code so far:

#pragma mark - NSURLConnection methods

- (void)htmlRequest
{
    // Create the request.
    NSURLRequest *theRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.mywebsite.com/index.html"]
                                              cachePolicy:NSURLRequestReloadIgnoringCacheData
                                          timeoutInterval:60.0];

    // create the connection with the request
    // and start loading the data
    NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
    if (theConnection) {
        // Create the NSMutableData to hold the received data.
        // receivedData is an instance variable declared elsewhere.
        receivedData = [NSMutableData data];
    } else {
        // Inform the user that the connection failed.
        NSLog(@"Connection Fail");
    }
}


- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    // This method is called when the server has determined that it
    // has enough information to create the NSURLResponse.

    // It can be called multiple times, for example in the case of a
    // redirect, so each time we reset the data.

    // receivedData is an instance variable declared elsewhere.
    [receivedData setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{

    // Append the new data to receivedData.
    // receivedData is an instance variable declared elsewhere.
    [receivedData appendData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    // inform the developer of error type

}

// This method uses methodName to determin which Initalizer method to send the response data to in EngineResponses.m
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
//    EngineResponses *engineResponses = [EngineResponses sharedManager];

//        [engineResponses GetManufacturers:receivedData];

    NSString *myString = [[NSString alloc] initWithData:receivedData encoding:NSUTF8StringEncoding];
    NSLog(@"%@", myString);

}

as you can see I am just calling index.html directly.. I would like to know how to format my request so i get the index.html as well as style.css

any help would be greatly appreciated.

Answer 1

I always create a new data structure,which has a -connection property and a -request property,like this

@interface connectionWrapper : NSObject
@property(retain) NSURLRequest *request
@property(retain) NSURLConnection *connection

by retaining this data structure in an mutable array, you can distinguish the connections in callback methods by iterate the array and compare each connectionWrapper instance's -connection property with the connection parameter the of the callback method, if they match(points to a same object), then you can retrieve the -request property of the connectionWrapper instance, then -url property of NSURLRequest instance.

as I'm not an native English speaker, I think code is a better tutor.

-(NSURLRequest*)getRequestByConnection:(NSURLConnection*)connection
{
    for(connectionWrapper *w in theArrayContainingAllConnectionWrappers)
    {
        if(w == connection)
            return w.request;
    }
}

In callback method:

-(void)connection:(NSURLConnection*)connection didReceiveResponse(NSURLResponse*)response
{
    NSURLRequest *request = [self getRequestByConnection:connection];
    NSURL *url = [request url];
    /*apply different approach to different url/*
}

PS:it's very sad that NSURLConnection don't have a -request property so that we can retrieve the request associated with the connection easily.

Answer 2

One way or another, you will have to make 2 requests. Even if you open a web page directly in a web browser, the browser will make a separate request for the CSS file referenced in the HTML it downloads. If your application needs both the HTML and the CSS file, then you want it to make 2 separate URL requests, first to get the HTML and then to get the CSS file.

Now, just because 2 requests need to be made, that doesn't mean you will always need to write the code that makes those 2 requests. It may be that libraries like the ones recommended by @Slee automatically take the results of a first request, parse them out, and make requests for any referenced CSS files. I have not worked with them so I am not sure what they support, or if any libraries will do this for you.

One thing you may want to consider is loading the HTML and CSS through a UIWebView rather than handling it all manually. UIWebView will attempt to load, parse, and render an HTML file into a UI component. In the process it will load referenced CSS and JavaScript files and apply them to its rendering. If you want to do anything special like intercept the calls it makes to load the CSS file(s), you can implement the UIWebViewDelegate protocol and set the delegate of the the UIWebView. Within that delegate you can implement the -webView:shouldStartLoadWithRequest:navigationType: method to be notified when the web view is loading the CSS file. You can use the call to that method to look at the request that is being issued for the CSS and do something else interesting with the request.

Answer 3

do you know the name of the .css file?

If so I would just make 2 requests otherwise you will have to write a parser to look for the link to the css and make a second request anyways.

I'd also suggest looking into a library to handle the downlading of stuff - lot's of great libraries that can do the heavy lifting for you with advanced features.

Here's 3 I have used:

http://blog.mugunthkumar.com/coding/ios-tutorial-advanced-networking-with-mknetworkkit/

https://github.com/tonymillion/TMHTTPRequest

https://github.com/pokeb/asi-http-request